Add dummy appveyor / fix missing install

Author: johanneswuerbach

.github/workflows/ci.yml

@@ -17,6 +17,7 @@ jobs:
       - uses: actions/setup-node@v1
         with:
           node-version: 12
+      - run: npm ci
       - run: npm run lint
 
   test:

appveyor.yml

@@ -0,0 +1,12 @@
+# Remove after disabling appveyor, dummy to prevent red status
+
+# Install scripts. (runs after repo cloning)
+install:
+  - echo noop
+
+# Post-install test scripts.
+test_script:
+  - echo noop
+
+# Don't actually build.
+build: off